Department of Urology, University of Tuebingen, Tuebingen, Germany.
Oncol Rep. 2010 Jan;23(1):159-63.
The altered expression and activation of the mammalian target of rapamycin (mTOR) promotes the invasiveness and metastatic potential in a variety of malignancies. The aim of the present pilot study was to determine mTOR expression in clear cell renal cell carcinoma (RCC) and to evaluate mTOR activation and phosphorylation at Ser2448. Tissue microarray immunohistochemistry and Western blot analysis of tumor and benign tissue from 10 patients subjected to tumor nephrectomy were investigated. Staining of mTOR and phosphorylated-mTOR (p-mTOR) was documented and determined as percentage of the maximum. Western blots were evaluated densitometrically. Ratios of tumor versus benign tissue were calculated and compared by the Wilcoxon/Kruskal-Wallis test. Immunohistochemical expressions of mTOR and p-mTOR were 49 and 40% in benign renal parenchyma, whereas it was 20 and 42% in tumor tissue. Ratios of tumor versus benign tissue revealed a reduction to 0.44 for mTOR and corresponding elevation to 1.29 for p-mTOR (p<0.05). The rate of p-mTOR to mTOR was 1.19 in benign, whereas it was 5.30 in tumor tissue. Western blot densitometry detected lower expressions of mTOR in tumor compared to benign tissues. Ratio of p-mTOR to mTOR were significantly different in benign versus tumor tissue (0.86 vs. 1.37; p<0.04). The observation that RCC specimens exhibit higher levels of p-mTOR in RCC compared to benign renal parenchyma indicate the role of mTOR phosphorylation in RCC tumor development and progression. This study found a concomitant reduction of the RCC mTOR protein expression, which suggests that elevated levels of activated p-mTOR result predominantly from an increased mTOR phosphorylation rather than from protein overexpression. These pilot study results may contribute to the clarification of mTOR-pathway regulation processes in RCC on the way to the protein profiling-predicted targeted therapy.
哺乳动物雷帕霉素靶蛋白（mTOR）的表达和激活改变可促进多种恶性肿瘤的侵袭性和转移潜能。本初步研究旨在确定肾透明细胞癌（RCC）中的 mTOR 表达，并评估 mTOR 激活及其丝氨酸 2448 位磷酸化。对 10 例行肿瘤肾切除术的患者的肿瘤和良性组织进行组织微阵列免疫组织化学和 Western blot 分析。记录并确定 mTOR 和磷酸化-mTOR（p-mTOR）的染色百分比作为最大值。通过 Western blot 进行密度分析。通过 Wilcoxon/Kruskal-Wallis 检验比较肿瘤与良性组织的比值。mTOR 和 p-mTOR 在良性肾实质中的免疫组化表达分别为 49%和 40%，而在肿瘤组织中分别为 20%和 42%。肿瘤与良性组织的比值显示 mTOR 降低至 0.44，相应的 p-mTOR 升高至 1.29（p<0.05）。p-mTOR 与 mTOR 的比率在良性组织中为 1.19，而在肿瘤组织中为 5.30。Western blot 密度检测到肿瘤组织中 mTOR 的表达低于良性组织。良性组织与肿瘤组织中 p-mTOR 与 mTOR 的比值差异有统计学意义（0.86 比 1.37；p<0.04）。与良性肾实质相比，RCC 标本中 RCC 中 p-mTOR 水平升高的观察结果表明 mTOR 磷酸化在 RCC 肿瘤发生和发展中的作用。本研究发现 RCC 中 mTOR 蛋白表达的同时降低，这表明激活的 p-mTOR 水平升高主要归因于 mTOR 磷酸化增加而不是蛋白质过表达。这些初步研究结果可能有助于阐明 RCC 中 mTOR 通路调节过程，进而为蛋白质谱预测的靶向治疗提供依据。
